I am a skeptic of these things as per what the media and the whole UFOlogy thing in general describe and claim.
One of the problems with the argument of it being a craft from a distant star is they show up on RADAR!
If I were to visit a civilization that couldn't answer the questions that I have about themselves I wouldn't make the craft of metal. Why? If I needed a craft to explore the surface of a planet that had a thick atmosphere I'd make it atmospherically buoyant that way it could hover over areas when needed without having to expend energy. Second I would give the craft the ability to fly at hypersonic to orbital speeds. Thirdly I wouldn't have the craft manned since transporting the kitchen sink and bathroom across interstellar space is unnecessary.
To make a vehicle as described above I would need to develop a
material that is lighter than air and stronger than steel. This material could then create a craft that internally is a vacuum so there is no need for a gas like hydrogen or helium to displace the air inside the craft. Its outer surface could be used to create an inverted jet engine. Where cool air from one side of the craft is sucked across its surface to an area that is heated to a very high temperature. Using nano-technology a smart alien could make micro-batteries and align the atoms to exploit the vast electrical power of atoms. These nano-batteries not only provide the heat to move the air but can also cool the incoming air as the craft reaches hypersonic speeds. This allows the craft's inverted ram-jet to continue to provide thrust beyond the hypersonic velocities! Because the craft is soo light it can accelerate itself to orbital velocity.
Oh and I'd make the craft stealth to radar and probably visibly as well so I could monitor the inhabitants without interfering with their natural behaviors. Making the craft clear like plexiglass is not an impossible feat if our alien visitors are masters of atoms!
The ability to communicate FTL has been done with
quantum ghost imaging. Where entangled photons can detect each other's interactions. Think of being able to build a transceiver where each side uses a polarization filter than can be controlled. Where, as I modify the filter to form a shape the image of the shape appears on the other side instantly! So communicating across interstellar space just might be possible. So why would I send bio-bags filled with water? I'm better off sending nano-space ships that require a fraction of the energy to propel to distant stars. So what energy could a nano-spaceship use to cross the galaxy? Electric fields of stars and gas giants. Despite the nano-ships can travel fast something like 10 to 99 percent of the speed of light becomes problematic. Why? Because the true speed limit to cross space is not the speed of light but the speed that a ship can withstand a collision with some trivial piece of dust. Why large spaceships moving near the speed of light is not possible, if they strike a microscopic piece of material in space the impact would be like that of an atomic bomb. So ET probably would just send nano-probes that they can remote-sense using an entangled-transceiver.
Since the nano-ships are soo small they can only carry DNA like information on how to build whatever they need at their destination, like the buoyant aircraft described earlier and inclusive of the ability to make the probes look like the life living on our planet. The next time you look at your neighbor, boss, boyfriend, or girlfriend, ask them more questions about where they're from, you just never know it just might be ET.
OF course, if the expressway to the galaxy is using nano-technology then it explains Fermi's paradox. The more technologically advance an intelligent species becomes the smaller and more energy-efficient is their technology. It's kinda hard to see a space-ship the size of an insect or smaller positioning itself in orbit...